Jensen Box

The Jensen Box was developed by UC Berkeley psychologist Arthur Jensen as a standard apparatus for measuring choice reaction time, especially in relationship to differences in intelligence [A. R. Jensen. (1987). Individual differences in the Hick paradigm. In "Speed of information-processing and intelligence." P. A. Vernon and et al., Norwood, NJ, USA, Ablex Publishing Corp, 101-175. ] . Since Jensen energised this paradigm, correlations between simple and choice reaction time have been demonstrated in many hundreds of studies. Perhaps the best was reported by Ian Deary and colleagues, in a population-based cohort study of 900 individuals, demonstrating correlations between IQ simple and choice reaction time of -.3 and -.5 respectively, and of -.26 with the degree of variation between trials shown by an individual [I. J. Deary, G. Der and G. Ford. (2001). Reaction times and intelligence differences: A population-based cohort study. "Intelligence", 29, 389–399. ] .

The standard box is around 20 inches wide and 12 deep, with a sloping face on which 8 buttons are arrayed in a semi-circle, with a 'home' key in the lower centre. Above each response button lies a small led which can be illuminated, and the box contains a speaker to play alerting sounds.

Following Hick's law [* cite journal|author=Hick, W. E.|year=1952|title=On the rate of gain of information|journal=Quarterly Journal of Experimental Psychology|volume=4|pages=11–26|doi=10.1080/17470215208416600] , reaction times (RTs) slow as a log₂ of the number of choices are presented: Thus when all but one button is covered responses are fastest, and slowest when all 8-responses are available.

Several parameters can be extracted: The mean 1-choice RT gives simple reaction time. The slope of the function across 1,2,4, and 8 lights gives the rate of information processing, an variance or standard deviation in RTs can be extracted to give a measure of response variability within subjects.

Finally, the time to lift off the home button and the time to hit the response button can be measured separately, and these are typically thought of as assessing decision time, and movement time, though in the standard paradigm, subjects can shift decision time into the movement phase by lifting off the home button while the location computation is still incomplete. Masking the stimulus light can eliminate this artifact [Bates, T. C., & Stough, C. (1998). Improved Reaction Time Method, Information Processing Speed, and Intelligence. Intelligence, 26(1), 53-62.] .Simple reaction time correlates with IQ, and there is some evidence that the slope of responding does also, so long as access to the stimulus is controlled.

The Jensen Box

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